1. Field of the Invention
The present invention relates to a pickup device for use in a disk player such as a compact disk player.
2. Description of Related Art
Among conventional pickup devices, there are devices having a structure such as that shown in FIGS. 6, 7, 8A and 8B. Such a pickup device includes, as shown in an exploded perspective view in FIG. 6, a fixed portion 1 in the associated disk player, and four elastic support members 2, such as plate spring members, which each have a first end portion secured to the fixed portion 1, a second end portion secured to a pickup body 3 and a displaceable portion therebetween. The pickup body 3, to which the second end portions of the elastic support members 2 are secured, has an objective lens 3a on the upper (as viewed in FIG. 6) surface thereof. Focusing windings 4 are mounted on two opposing side surfaces of the pickup body 3.
Focusing members 7 are provided on another fixed portion of the disk player 1 in correspondence with the focusing windings 4. Each focusing member 7 comprises a plate-shaped magnet 5 and a U-shaped yoke 6, the magnet 5 being secured to one of the free-end sections of the yoke 6. Each of the focusing windings 4 is loosely fit in the gap between two opposing free-end sections of the corresponding focusing member 7 so that the pickup body 3 is controlled to move in the direction of the arrow A shown in FIG. 6.
Each of the elastic support members 2 has its two end portions secured to the pickup body 3 and the fixed portion 1 by an ultraviolet-curing adhesive 8 (abbreviated to "adhesive" throughout the specification unless otherwise specified). The adhesive 8 is used to meet the requirements that the entire structure should be made light and simple. The ultraviolet-curing adhesive 8 has the characteristic of instantaneously curing upon the radiation of ultraviolet light, and gradually curing with the passage of time.
An end portion of each elastic support member 2 is secured to the pickup body 3 or the fixed portion 1 by the adhesive 8 in the following manner. Before the elastic support member is overlapped with the pickup body 3 or the fixed portion 1, a quantity of the adhesive 8 is coated on the two end portions of each elastic support member 2. Then, one of the coated portions of the member 2 is contacted, under pressure, with a portion of the upper or lower surface of the pickup body 3.
However, with this state of the contacted portion, even when ultraviolet light is radiated from an upper position as viewed in FIG. 6, the adhesive positioned between the pickup body 3 and the elastic support member 2 cannot be irradiated with the ultraviolet light and, hence, cannot be instantaneously cured. For this reason, the conventional practice has been adapted to achieve an initial bond strength in the following manner. As shown in FIGS. 8A (a side view of a securing portion where an elastic support member 2 is secured to the pickup body 3) and FIG. 8B (an enlarged top view of the securing portion), a further quantity of the adhesive 8 is coated in such a manner as to keep it on a region including the pertinent end of the elastic support member 2, and the heaped adhesive is irradiated with ultraviolet light to be instantaneously cured. Then, that fraction of the adhesive 8 applied between the elastic support member 2 and the pickup body 3 is allowed to cure with the passage of time.
If an initial bond strength is achieved in this manner, it is possible to start the subsequent processes before all of the applied adhesive is cured; this is advantageous in that the time required for manufacturing the pickup device can be decreased.
However, the above-described art entails a problem. When an elastic support member 2, partially coated with a quantity of adhesive 8, is contacted with the pickup body 3 under pressure, a part of the adhesive 8 is pushed out to a displaceable portion 2a of the member 2, as denoted by 8a and 8b in FIG. 7 (a fragmentary side view of the pickup body 3). Pushed out adhesive portions, such as 8a and 8b, disturb the displacement characteristic of the displaceable portions 2a of the elastic support members 2 to make it into a non-linear characteristic. In addition, the pushed out adhesive portions cause a deviation in the center frequency of the portions 2a.
Another problem is that, if, in order to achieve an initial bond strength, the conventional practice is adopted and a further quantity of adhesive 8 is applied by keeping it on a region including the end of each elastic support member 2, this necessitates the consumption of an additional amount of adhesives. In addition, the external appearance of the pickup device is spoiled, thereby lowering the value of commodity of the device.